Field of the Invention
The present invention relates to prosthetic heart valve assemblies and methods of preventing paravalvular leakage. More specifically, the present invention relates to the use of sealing members to seal gaps that can form between a valve frame and the wall of a native annulus when a prosthetic heart valve is implanted in the native annulus.
Background
Minimally invasive approaches have been developed to facilitate catheter-based implantation of valve prostheses on the beating heart, intending to obviate the need for the use of classical sternotomy and cardiopulmonary bypass. For example, International Application (PCT) Nos. WO 93/01768 and WO 97/28807, as well as U.S. Pat. No. 5,814,097 to Sterman et al., U.S. Pat. No. 5,370,685 to Stevens, and U.S. Pat. No. 5,545,214 to Stevens illustrate techniques for transcatheter implantation of stents and prosthetic valves that are not very invasive, as well as instruments for implementation of these techniques.
Although transcatheter delivery methods have provided safer and less invasive methods for replacing a defective native heart valve, leakage between the implanted prosthetic valve and the surrounding blood vessel is a recurring problem. Leakage can be particularly prevalent at the location of the commissural points of the native valve leaflets. At these commissural points, a gap can exist between the prosthetic valve frame and the wall of the native annulus. Attempts have been made to provide structures on the prosthetic valve to prevent leakage.
For example, U.S. Patent Publication No. 2007/0293944 to Spenser et al. (“Spenser”) discloses methods of percutaneously repairing paravalvular leaks, including repair techniques and built-in leak prevention means. In one embodiment, a prosthetic valve is provided with flexible, self-expanding elements connected to the outer surface of the prosthetic valve. The self-expanding elements are positioned at even intervals around the surface of the prosthetic valve. A self-expanding element will expand if there is a gap between the implanted valve and the body lumen at the location of the self-expanding element, but will remain collapsed at the locations where the valve more closely abuts the body channel.
One disadvantage of this device arises because the prosthetic valve is designed for percutaneous implantation. Percutaneous transcatheter implantation requires a longer catheter than more direct transcatheter implantation methods such as delivery directly through the thoracic aorta or the apex of the heart. The longer catheter length limits the physician's ability to control the orientation of a prosthetic valve on the catheter. Because of this lack of control, it is difficult to align sealing elements directly with known inconsistencies of a native annulus, such as the gap that typically appears between the prosthetic valve and the wall of the native annulus at the commissural points of the native valve leaflets. Providing sealing elements at standard intervals along the circumference of the prosthetic valve does not guarantee that a particular gap between the prosthetic valve and the native annulus wall is filled with a sealing element. The valve may ultimately be positioned such that one of the empty spaces between two sealing elements is aligned partially or completely with a gap, thereby failing to prevent leakage through the gap.
Thus, there is a need for a prosthetic heart valve that can more accurately and predictably seal paravalvular leakage points by providing targeted commissural seal.